Long played only the first half but repeatedly troubled United's defense with runs from the right flank into central areas, often getting past defenders Patrick Dorgu and Ayden Heaven. He unleashed several long-range efforts, narrowly missing the target, particularly in the early first half.
His performance quickly gained attention from fans and pundits.
ESPN gave him 7.5, the highest score of ASEAN All-Stars players in the friendly.
The United Stand, a popular fan channel, commented: "25 minutes. Pretty even game so far. Can we sign All Stars number 9? Causing our defense serious issues with every attack."
Malaysian journalist Avineshwaran of The Star wrote: "Hai Long is playing with confidence, dribbling past everyone with ease."
Asian football expert Gabe Tan shared the same stance, saying: "I'm not kidding. The ASEAN All-Stars played much better than Manchester United. Hai Long caused all kinds of problems for the defense from the right."
On social media, fans also showed admiration for the 24-year-old midfielder. One X user even joked about a trade as he wants to swap Hai Long for Rasmus Hojlund. Both players wore the number 9 jersey, but while Hai Long impressed, Hojlund struggled and frequently lost possession.
German club Werder Bremen's Facebook page in Vietnam also joined the conversation: "Keep an eye on your phone after the match, Hai Long."
Long trained at the Viettel FC Academy before returning to his hometown youth club in Quang Ninh Province. He made his professional debut in the V. League and joined Hanoi FC in 2022. The 1.68 m tall midfielder has tallied 14 goals in 95 V. League appearances and scored twice for Vietnam in the 2024 ASEAN Cup, including a long-range strike that sealed victory in the final's second leg against Thailand in Bangkok.
Long was one of four Vietnamese players selected for the ASEAN All-Stars squad. Nguyen Hoang Duc, Nguyen Van Vi and Do Duy Manh came on in the second half. The match's only goal came from Myanmar's Maung Maung Lwin, who finished off a brilliant assist from Australian youngster Adrian Segecic.
This match marked the first time Manchester United played a friendly right after the end of a season. The club reportedly earned $11 million from the friendlies against the ASEAN All-Stars and an upcoming match in Hong Kong. Despite fielding key players like Bruno Fernandes, Harry Maguire, Casemiro and Amad Diallo, United could not make a comeback and eventually suffered a 0-1 defeat.